#include <stdio.h>

int main()
{
	int a[100] = {0};
	freopen("test.in", "r", stdin);
	freopen("test.out", "w", stdout);
	int n = 0;
	scanf("%d", &n);
	for ( int i = 0; i < n; i++ ) {
		scanf("%d", &a[i]);
	}
	
	for ( int i = 0; i < n - 1; i++ ) 
	{
		for ( int j = 0; j < n - i - 1; j++ ) 
		{
			if ( a[j] > a[j+1] ) {
				int tmp = a[j];
				a[j] = a[j+1];
				a[j+1] = tmp;
			}
		}
	}
	
	float mid = 0;
	if ( n % 2 != 0 ) {
		mid = a[n/2];
	}
	else {
		mid = (a[n/2 - 1] + a[n/2]) / 2.0;
	}
	printf("%.2f", mid);
	fclose(stdin);
	fclose(stdout);
	return 0;
}
